It depends on the motor. Most glow (nitro) engines do require a break in. How to break it in should be in the instructions for the engine. Some engines, such as the Evolution engines, clame they are already broken in. I still believe that you should run up any engine before you go out to fly, just to work out the needle valve and transmitter adjustments. If you don't have any instructions for the enigne, I'd recomend looking online at the engine manufacture's website. Most provide instructions for their engines that you can print out.